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Miyabe, Masabumi; Satou, Yukihiko; Wakaida, Ikuo; Terabayashi, Ryohei*; Sonnenschein, V.*; Tomita, Hideki*; Zhao, Y.*; Sakamoto, Tetsuo*
Journal of Physics B; Atomic, Molecular and Optical Physics, 54(14), p.145003_1 - 145003_8, 2021/07
Times Cited Count：0 Percentile：0.01(Optics)Two-color two-step photoionization optogalvanic spectroscopy was performed using high-repetition-rate titanium sapphire lasers and a uranium hollow cathode lamp to find the two-step resonance ionization schemes of uranium. Many ionization transitions were observed by exciting uranium atoms in a ground state into five, even parity, excited levels with the first-step laser and by scanning the second-step laser wavelengths. By blocking the first-step laser, single-color, two-photon ionization transitions were also identified. From these results, we have found more than 50 odd-parity autoionizing levels of uranium in the energy, ranging from the ionization potential (49958.4 cm
) to 51150 cm. The determined energy levels are within 1 cm of previously reported values.
Sato, Tetsuya
Kagaku To Kogyo, 72(10), P. 867, 2019/10
We conducted measurements of the first ionization potential (IP
) of the heavy actinide elements, lawrencium (Lr, 
), nobelium (No, 
), mendelevium (Md, 
) and fermium (Fm, 
) by using a novel method based on a surface ionization process. The IP measurements have been performed using the ISOL (Isotope Separator On-Line) system equipped with a surface ion-source with short-lived heavy actinide isotopes, 
Lr (
= 27s), 
No ( = 24.5s), 
Md ( = 4.27 min), and 
Fm ( = 2.6 min). Our experimental results clearly showed that the IP of Lr is distinctly low among actinide elements. Moreover, No has the highest IP among them due to its full-filled 5f and 7s orbitals; the IP value increased with an atomic number up to No and decreased dramatically at Lr, indicating the similar trend with that of heavy lanthanide elements. Therefore, we concluded Lr would be the last member of the actinide series.
Takahashi, Fumiaki
Genshiryoku No Ima To Ashita, p.106 - 109, 2019/03
The Atomic Energy Society of Japan has planned to publish a document for public, entitled "Current and tomorrow of atomic energy, -Experiences from the accident at the Tokyo Electronic Power Company Fukushima Dai-ichi NPPs-". The documents give us basics and usages of radiations, in addition to nuclear power plants and the accident at TEPCO Fukushima Dai-ichi NPPs. This manuscript explains interactions and penetrations in material for 
-rays, 
-rays, 
-rays and neutrons. In addition, exposure characteristics that is determined by properties of radiations are expressed here. This manuscript also explains characteristics in internal exposure and countermeasures of radiation protection following the TEPCO accident for Iodine-131 and Cesium-137.
Taguchi, Shigeo; Miyauchi, Hironari*; Horigome, Kazushi; Yamamoto, Masahiko; Kuno, Takehiko
Bunseki Kagaku, 67(11), p.681 - 686, 2018/11
In thermal ionization mass spectrometry, de-gassing is one of the important treatments to release impurities of filaments and to minimize the influence of background. In this work, the effect of the surface change in the tungsten filament induced by the conductively heating treatment on uranium isotopic (
U/
U) measurement has been investigated. It was found that the conductively heating treatment of the filament has the effect of smoothing the surface of the filament and also has the effect of improving the deposition of the sample on the filament surface. As a result of either these effects, the precision of uranium isotopic (U/U) measurement was improved.
Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Beerwerth, R.*; Kaneya, Yusuke*; Makii, Hiroyuki; Mitsukai, Akina*; Nagame, Yuichiro; Osa, Akihiko; Toyoshima, Atsushi; et al.
Journal of the American Chemical Society, 140(44), p.14609 - 14613, 2018/11
Times Cited Count：29 Percentile：69.46(Chemistry, Multidisciplinary)The first ionization potential (IP) yields information on valence electronic structure of an atom. IP values of heavy actinides beyond einsteinium (Es, Z = 99), however, have not been determined experimentally so far due to the difficulty in obtaining these elements on scales of more than one atom at a time. Recently, we successfully measured IP of lawrencium (Lr, Z = 103) using a surface ionization method. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP among the actinide elements owing to its full-filled 5f and the 7s orbitals. In the present study, we have successfully determined IP values of No as well as fermium (Fm, Z = 100) and mendelevium (Md, Z = 101) using the surface ionization method. The obtained results indicate that the IP value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids.
Baba, Yuji; Shimoyama, Iwao
Photon Factory Activity Report 2017, 3 Pages, 2018/00
When a solid is heated in vacuum, a part of the surface layer desorbs as ions, which is known as "surface ionization". In this report, we present the results for surface ionization of bulk cesium chloride (CsCl). When the positive potential was applied to the sample, we found that the Cs
ions were desorbed at around 410 
C, which is lower than the melting point of CsCl (645 C). The low desorption temperature was explained by the changes in the work function of the CsCl surface. As an application, we also investigated the desorption of Cs ions from Cs-adsorbed soil. When Cs-adsorbed soil was heated at 460 C for 2 hours, about 13% of Cs was desorbed as Cs ions. The results suggest that the surface ionization would possibly be applied to the desorption of Cs from contaminated soil.
Okubo, Ayako; Shinohara, Nobuo; Magara, Masaaki
Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.231 - 234, 2017/10
Times Cited Count：2 Percentile：19.65(Chemistry, Analytical)The model date of two enriched uranium materials were determined using a new method for nuclear forensics investigation. In this method, the 
Th/
U ratio was calculated without spike addition from measured ratios of Th/Th and U/U, and calculated Th/U ratio in secular equilibrium. The obtained model date for the low-enriched uranium material was agreed with the known production date within uncertainty. For the highly enriched uranium material, slightly younger model date than the known production date was obtained. The U interference on Th counting in thermal ionization mass spectrometry measurement was suspected as a potential cause.
Sato, Tetsuya
Genshikaku Kenkyu, 61(1), p.96 - 106, 2016/09
We successfully determined the first ionization potential of lawrencium (Lr, Z=103). The result experimentally substantiated for the first time that Lr is the last member of the actinide series. Measured ionization potential suggested that Lr atom would have the electronic configuration which is different from the configuration expected based on the Periodic table. For the measurement, we have developed a novel method applied the surface ionization process. Public responses after the publication are also introduced.
Sato, Tetsuya
Isotope News, (740), p.16 - 19, 2015/12
We successfully determined the first ionization potential of lawrencium (Lr, Z=103). The result experimentally substantiated for the first time that Lr is the last member of the actinide series. Measured ionization potential suggested that Lr atom would have the electronic configuration which is different from the configuration expected based on the Periodic table.
Sato, Tetsuya
Nihon Genshiryoku Gakkai-Shi ATOMO
, 57(11), p.741 - 744, 2015/11
We have experimentally confirmed that Lr would be the last member of actinides series for the first time by a measurement of the first ionization potential of lawrencium (Lr, element 103). The electronic orbital of Lr atom which is estimated by the result suggests that Lr could have the outermost electronic orbital similar with group-13 elements. This work triggered a discussion concerning positions of Lr and lutetium, lanthanide homologue of Lr.
Sato, Tetsuya
Hosha Kagaku, (32), p.34 - 41, 2015/09
In the surface ionization process, an ionization efficiency depends on the first ionization potential of the atom of the element. The ionization potential can be estimated by using the relationship. This method has been developed in order to determine the first ionization potential of lawrencium (Lr, element 103). The value of the ionization potential of Lr have not been measured experimentally due to its low production rate and short half-life. The surface-ionization method is described in detail in this paper.
Sato, Tetsuya; Nagame, Yuichiro; Tsukada, Kazuaki
Kagaku To Kogyo, 68(9), p.824 - 826, 2015/09
We successfully confirmed that lawrencium (Lr, element 103) is the last member of actinide series by a measurement of its first ionization potential. Obtained experimental result suggested that the outermost electronic orbital of Lr atom would have p-orbital similar to elements of group-13. Our result triggered again the discussion of the position of Lr and lutetium, the lanthanide homologue of Lr, on the Periodic Table.
Sato, Tetsuya
Saiensu Potaru (Internet), 3 Pages, 2015/07
On April 9th, a press release titled "Measurement of the first ionization potential of lawrencium (element 103) - Unravelling Relativistic Effects in the Heaviest Actinide Element -" was issued. This research result published from Nature was not only introduced in its "News & Views" but also appeared on the cover. I made a commentary on the result and introduced its response for public.
Esaka, Fumitaka; Suzuki, Daisuke; Magara, Masaaki
Analytical Chemistry, 87(5), p.3107 - 3113, 2015/03
Times Cited Count：13 Percentile：44.45(Chemistry, Analytical)The analysis of uranium particles in environmental samples taken from nuclear facilities is a useful tool to unveil undeclared nuclear activities related to the production of nuclear weapons. An efficient method to analyze isotope ratios of individual uranium particles is thermal ionization mass spectrometry (TIMS) combined with a fission track technique. A drawback in the fission track-TIMS technique is so-called particle-mixing. Here, some uranium particles are measured as a single particle and an averaged isotope ratio is obtained, which may lead to misunderstanding conclusions for source identification. In the present study, micro-sampling under a scanning electron microscope has been added to the procedure of the fission track-TIMS technique. The analysis of a mixed sample containing uranium particles in SRM 950a and CRM U100 materials indicated that the problem of particle mixing was almost avoidable with the proposed technique.
Kusama, Yoshinori
Purazuma Shindan No Kiso To Oyo, p.195 - 205, 2006/03
no abstracts in English
Moribayashi, Kengo; Lee, K.*; Kagawa, Takashi*; Kim, D. E.*
Laser Physics, 16(2), p.322 - 324, 2006/02
Times Cited Count：1 Percentile：7.24(Optics)no abstracts in English
Moribayashi, Kengo; Kagawa, Takashi*; Kim, D. E.*
Journal of Plasma and Fusion Research SERIES, Vol.7, p.233 - 236, 2006/00
no abstracts in English
Moribayashi, Kengo
Journal of Plasma and Fusion Research SERIES, Vol.7, p.150 - 153, 2006/00
no abstracts in English
Daido, Hiroyuki; Yamaguchi, Naohiro*; Midorikawa, Katsumi*; Kawachi, Tetsuya; Moribayashi, Kengo
Reza Handobukku Dai-2-Han, p.325 - 335, 2005/04
no abstracts in English
Ebisawa, Noboru; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Seki, Norikazu*; Oga, Tokumichi; Ikeda, Yoshitaka
Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03
no abstracts in English
